1. Field of the Invention
The present invention relates to a hybrid camera, which can selectively use either a silver-halide-type photographic film or a photoelectric-conversion-type image sensor to record an optical objective image, obtained through a photographing optical system, thereon.
2. Description of the Related Art
Recently, an electronic still video camera, which includes a photographing optical system for forming an optical objective image, a photoelectric-conversion-type image sensor, such as a CCD (charge-coupled device) image sensor, for converting the optical objective image into a frame of image-pixel signals, and a memory medium, such as an IC memory card, a floppy disk and so on, for storing the frame of image-pixel signal in the memory medium, has become popular.
On the other hand, a hybrid camera, which can selectively use either a silver-halide-type photographic film or a photoelectric-conversion-type image sensor to record an incident optical objective image, obtained through a photographing optical system, has been developed. In a hybrid camera, usually either a pressure-plate unit or an image sensor unit is detachably assembled in an inner space of a releasable back-cover of a camera body, allowing the two units to be selectively interchangeable with each other. The pressure-plate unit includes a resiliently-biased plate element, and the image sensor unit includes a photoelectric-conversion-type image sensor, such as a CCD image sensor.
When a hybrid camera is used as a conventional camera, i.e. when a hybrid camera is charged with a film cartridge containing a roll of silver-halide-type photographic film, the pressure-plate unit is initially assembled in the inner space of the releasable back-cover, so that a frame section of the silver-halide-type photographic film is exactly positioned on an image-forming plane, defined by a photographic optical system, by the resiliently-biased plate element of the pressure-plate unit.
When the hybrid camera is used as an electronic still video camera, the pressure-plate unit is exchanged for the CCD image sensor unit. Namely, the image sensor unit is assembled in the inner space of the releasable back-cover. When the back-cover is closed, an image-sensing surface of the CCD image sensor is positioned on the image-forming plane of the photographing optical system, and thus an optical image to be photographed is formed and correctly focused on the image-sensing surface of the CCD image sensor.
As is apparent from the foregoing, in a conventional hybrid camera, whenever one of the two functions is selected in place of the other, the pressure-plate unit and the image-sensor unit must be interchanged. Of course, the interchanging of the units is time consuming and troublesome for the user.
Therefore, an object of the present invention is to provide a hybrid camera, selectively using either a silver-halide-type photographic film or a photoelectric-conversion-type image sensor to record an incident optical objective image, obtained through a photographing optical system, wherein a recording of the optical image on one of the photographic film and the image sensor can be automatically and reliably selected without involving any burdensome manual manipulation.
In accordance with the present invention, there is provided a hybrid camera selectively using either a photographic film or a photoelectric-conversion-type image sensor to record an incident optical objective image, obtained through a photographing optical system. The hybrid camera comprises a movable assembly, which is shiftable along an optical axis, defined by the photographing optical system, between a first photographing position and a second photographing position. The photographic film and the photoelectric-conversion-type image sensor are mounted on the movable assembly. The hybrid camera further comprises a driver, which selectively drives the movable assembly, such that the movable assembly is positioned at either the first photographing position or the second photographing position. When the movable assembly is positioned at the first photographing position by the driver, an image-recording area of the photographic film is placed on an image-forming plane, defined by the photographing optical system. When the movable assembly is positioned at the second photographing position by the driver, an image-sensing area of the photoelectric-conversion-type image sensor is placed on the image-forming sensor of the photographing optical system.
Preferably, the movable assembly includes a constrainer for constraining the movement of the photographic film at a given location with respect to the movable assembly, and a transparent pressure-plate, a surface of which the constrained photographic film is placed against. The movable assembly may comprise a first subassembly and a second subassembly which are associated with each other. In this case, the constrainer is included in the first subassembly, and the transparent pressure-plate is included in the second subassembly. Also, the image-sensing area of the photoelectric-conversion-type image sensor is in contact with a second surface, being opposite the first surface, of the transparent pressure-plate. The transparent pressure-plate is preferably formed of a transparent glass material exhibiting an infrared-radiation-shielding characteristic.
The hybrid camera may further comprise a first resilient device for resiliently biasing the first subassembly against the second subassembly, and a second resilient device for resiliently biasing the second subassembly against the first subassembly, whereby the photographic film is resiliently pressed against the first surface of the transparent pressure-plate. Preferably, an urging force of the first resilient device is smaller than an urging force of the second resilient device, such that a resultant urging force resiliently biases the movable assembly toward the second photographing position, whereby the positioning of the movable assembly at the second photographing position by the driver is assisted by the second resilient device.
Also, the hybrid camera may comprise a film sensor for sensing an existence of the photographic film. In this case, the movable assembly, driven by the driver, is positioned at the first photographing position, when the existence of the photographic film is sensed by the film sensor, and the movable assembly, driven by the driver, is positioned at the second photographing position, when the existence of the photographic film is not sensed by the film sensor.
Further, the hybrid camera may comprise a determiner for determining whether the movable assembly is properly positioned at either the first photographing position or the second photographing position. In this case, a photographing operation is disabled when it is determined by the determiner that the positioning of the movable assembly at either the first photographing position or the second photographing position is irregular. Preferably, the hybrid camera comprises a display device for displaying a message, which announces that the photographing operation is prohibited, when the photographing operation has been disabled.
The driver may comprise at least one solenoid actuator, having a plunger associated with the movable assembly. The plunger of the solenoid actuator is selectively driven between a first operative position and a second operative position. In this case, the movable assembly is positioned at the first photographing position when the plunger is at the first operative position, and the movable assembly is positioned at the second photographing position when the plunger is at the second operative position.